Aerial target launching technique



Aug. 2, 1960 L. w. SEELEY ETAL 2,947,523

AERIAL TARGET LAUNCHING TECHNIQUE Filed Nov. 10, 1955 2 Sheets-Sheet 1 INVENTORS LEONARD W, SEELEY WILLIAM S. RONEY LEWIS A. STEVENS REGINALD R. VANCIL Aug. 2, 1960 L. w. SEELEY ETAL 2,947,523

AERIAL. TARGET LAUNCHING TECHNIQUE Filed Nov 10, 1955 2 Sheets-Sheet 2 INVENTORS LEONARD W. SEELEY WILLIAM S. RONEY LEWIS A. STEVENS REGINALD R. VANCIL 7 5. W ATTORNEYS The inventiondescrihed herein may be; mannfiactured and used: by-ortor the Government. at the; UnitedL'Statesi of America for governmentalwpurposesi withontsthenpaymentof ahyroyaltiesthereomorrthenefor.

This inventionqrelatesto methods and meanriifo staunching objfects-fromi the grounds to :beitowed byiaircraft andmore particularly to rzietlibdsnand; means iior 'ilaunchi n g high 'speedaeridtow targets: directly firom thetground iior With? the. advert-t of high speed aircraft and guided; missiles the: evaluation of tlre: controls of such guided missileszand of the fire control rapparatuswof such aircraft Similarly; realistic has: become: increasingly difficult. training of fighter pilots and aviation gunners has pre sentedaa problem; It hasahecomenecessary to=substantially abandon the banner andsleeve t-ype tow tar-gets previously used because of therexcessive drag'and v nlwhich is; inherent in such tow' targets. New target's, capable: of highspeed operation 'witlrrstability of flight and resistance to breakage, have been developed and these new targets. often take the form: t comparatively heavy, lengthy objects, made of rigid components. One'such target which has been particularly successfully used is the dart shapedassembly shown in the illustration of this invent-ion and, such-an assemble Sis specifically disclosed and-claimed in the copending United States; patent application; of Leonard WA Seel'ey; Serial Number 543,043, filed Qctoher 26., 1955?; now Patent No: 2,821,396. Targets'of such'design may obviously betconstructed of any chosen size, butter practical pu-rposesuare generally of'adequate length to give. good-visibilityand are, therefore, ofsubstantial Weight. For example; a dart shaped target twelve feet long and having other dimensions appropriate to such a length, weighs over one-hundred pounds-When constructed of A1 plywood.

The two main methods of launching-towtargets prior to this invention involved either dragging such targets from. the ground or releasing them from the tow .planeirr the air. The dragging method invariably'resu'ltstin major damage to the target and this is particularly true when such. rigid, lengthy, and heavy articles asthe new high speed target constructions areinvolved. Storing such targets in tow planes for release in'flight presents problems of stowage and of safety inseparating the targets from the tow planes. This invention is predicated on the basic discovery'that an object with a tow line attached thereto may be snatched from a stationary position on the ground by an aircraft in flight without dragging the object and with a minimum of forces applied thereto if the tow line is arranged for pick-up up-range from the object to be snatched rather than down-range ofv the object. It has been found; that with such an arrange ment, proper pilot technique will allow sate and damagefree pick-ups by aircraftflying: at? speeds considerably faster than one hundred miles per hour and-jthat'the initial movement of the object picked up is substantially nitecl States Patent meanssecuring the objectto bevertical when picked up in this manner so that there is no dragging of the object on the ground. It is, therefore, an object of this invention to provide a method' and means for launching objects from the ground for-aerial towing, without damaging such objectsor the towingaircraft.

It is a further and more specific object of this invention to provide a=-method and means for ground launching rigid high speed aerial tow targets for towing by an aircratt wherebythe target-s may be snatched from positions of rest on the ground by aircraft in flight Without damage to either the'aircraft orthe targets.

Other objects and many of the attendant advantagesof' this invention will be readily appreciated as the same becomesbetterunderstood by reference to the following; detailed description when considered in connection with" the accompanying drawings wherein:

Pig. 1 is ascheinatic showing ofthe ground. launchingtech-nique-which is the subject of-this invention, illustrating the requiredgi ound installation, theflight pattern of the aircraft; and the attitude of the tow line in various phases as the pick upg Fig. 2 is a fragmentary elevation of an aircraft suitably rigged with a towing hook for use in the technique deplated in Fig. 1

Fig. 3- is an elevational view of aground installation: suitable for practice oi? this invention, showing details of thetow line ofthe standards supporting the pick-up loop thereof for snatching by the aircraft, andof the picked up in positionfor thepi'ck-up. j

Referring now to the drawings in which like referencenumer als refer to like parts throughout, attention is partictiiar'ly directed to Fig. l, which schematically shows the operation of the entire technique. Thenovel con-I cept onwhichth'emethod of this invention-depends implementedby the physical arrangement of the necessary ground equipment so that the object to be picked up as a-tow target, is placed down-rangefrom thesta'nd ards which support the tow 'line for pickup, so that the towing aircraft picks up the entire tow line beforeit passes over thetarget, as shown-in Fig. 1.

The methed'eanbe ernployedby any aircraft, by the expedient of providing a hook which is supported'be health the fuselage and which is preferably releasable.

Many su'ch arrangements areobviously possible 'butf'onc exemplary-structure is illustrated in Fig; 2 to show how" naval aircraft equipped with conventional retractable arrestinggear hooks may be adapted for use in this method. In Fig. 2, aircraft 2 has the conventional tail hook 4-mounted on a yoke 6 which is attached to retracting means, not shown, operable from within the aircraft Attached to yoke 6, by any suitable means is a gripping and releasedevice '8 for releasablysupporting a towinghook 16. In the illustrative example, device8 is a conventional bomb rack of well known type, having" clamp-type jaws 1 d, steadying rest and rcleasecamill, and linkage means 14 operable from Within the. aircraft forj opening of grips 1-0 when desired. Bomb rack 8 is not ofthe-essence;of this invention and'therefore the details of the gripping jaws and of the release linkages are not given, -it'being obvi'ousthat any releasable ho-l'd'ingmeans could be substituted. Towing hook is is pmvidedfwith' lugs 18 of a shape to be gripped or held bythe jaws'l-(l and of such a length that the shaft-of the-towing -liook 3'16 will be steadiedbyzthe restltlt I i i The tow line structure, its relationshipto -the 'object to bepickecl tup or snatched, and; the tg rovZn equipine nt preferably *used tottaciIitateTpieleup, or snatch of Elie: article, :are illustrated 'in Fig. 3, in which "thetr msline- 320 is a suitable length of strong, flexible line. Both the nature of the line 20 and the length thereof may be varied. It has been found that line lengths in the order of 1800 feet give good results and that longer tow lines are eifec tive to compensate for poor pilot technique or to make possible the pick-up of larger loads. it has also been found that nylon line is particularly well suited, by weight, drag characteristics and elasticity, for use in this method, although lines of other size and of material of suitable strength, Weight and elasticity may obviously be used. Tow line 20 has swivel connectors 21, 22 at each of its ends and one of these swivel connectors 21 is connected to a pick-up loop 24 comprising 80 feet of line, while the connector 22 at the other end of the tow line is adapted to be connected to the object to be snatched, as for example a tow target 26, as illustrated.

The ground equipment used in this method comprises a pair of standards 28 each having a spring clip 30 adapted to releasably hold tow line loop 24, and a support 32 and stake 34 for positioning the object to be towed. Standards 28 are utilized as shown in perspective in inset I of Fig. 1, the loop 24 of the tow line 20 being stretched between the standards for pick-up by hook 16. The loop is supported on the down-range side of the standards by releasable spring clips 30 as shown in detail in Fig. 3. Support 32 and stake 34, shown in detail in Fig. 3, hold the object to be snatched in a preferred orientation for pick-up.

. It is inherent in this new pick-up method that the object to be picked up, as tow target 26, has a tendency to be pulled ip-range, prior to the pick-up, as the tow line is lifted by the towing aircraft. Such movement would result in unpredictable conditions and attitudes at the instant of pick-up and in possible damage to the tow target. This tendency is overcome by provision of stake means '34 suitably anchored in the ground and of a size to fit within an appropriate loop or eye element 35 which is provided on the object to be picked up. Thus, as may be seen from Fig. 3, stake 34 prevents horizontal movement of the tow target, but allows release of the target by vertical movement thereof. The positioning and support of the target is completed by use of supports 32 on either side of the target to engage portions thereof and maintain it substantially aligned with the proposed line of flight and out of contact with the ground for launching, as shown in Fig. 3.

The foregoing is a description of the equipment necessary to practice the novel method of this invention. The object to be towed is preferably provided with means to cooperate with stake 3 4 and with means for attachment to the tow line as described above. In the practice of this invention the object to be towed, as for example a tow target 26, is placed on an appropriate range area with its nose in the proposed direction of flight, with eyelet 35 thereof positioned on stake 34 and with surfaces thereof supported by supports 32, as shown in inset II of Fig. l and in Fig. 3. Tow line 20 is laid full length on the ground, on the up-range (direction of approach of the towing aircraft) side of the target, with the downrange end thereof being attached to the pivoted towing yoke 36 of the target by means of the swivel connection 22. Towing yoke 36 is pivoted substantially at the center of gravity as disclosed in the aforementioned US. Patent No. 2,821,396 which relates to the aerial tow target structure. The opposite (up-range) end of the tow line is attached, as by swivel connection 21, to the pick-up loop 24. Standards 28 are placed on either side of the line of flight in a position to receive and support loop 24 with a portion thereof stretched between the standards at an elevated point, as shown in Fig. 1 '(inset I andin Pig. 3, and the loop is releasably supported in the elevated position on the down-range side 'of the standards; by spring clips 30; Preferably the standards 28 and target26 are so ,placed that the tow line 20 may be loosely laid-thereb'etween, with no tension and no coiling.

With the target and ground equipment arranged as described hereinabove, an aircraft 2, with towing book 16 extended as shown in Fig. 2 is flown in the flight path illustrated by the line P over the imaginary ground pattern G, as shown in Fig. l. The towing aircraft is flown over the pick-up standards 28 toward the target 26 at such an altitude that its towing hook 16 engages the towing loop 24. The aircraft then climbs steadily up (as shown in Fig. 1), over and beyond the target 26. As the tow line lifts from the ground and the point of separation of the line from the ground approaches the target, the air load and inertia forces acting against the tow line shape it into what appears to be a modified catenary curve, as shown at K in Fig. 1. Since the only forces which can be applied by the line to the target must be in the direction of the line, the forces applied by the line are such as to strongly lift or raise the target 26 upwardly into the air without dragging it, such motion freeing the target from stake 34 and supports 32 and launching it for flight without damage. Because of the stretching of the tow line and the cushioning effect of the tow line catenary, the inertia forces on the target remain low.

At the end of the flight, the tow plane 2 flies over a designated drop area at an altitude of 600' to 800 feet over the ground. Tow hook 26 is then released by the pilot by mean-s best shown in Fig. 2, operation of the operating linkage 14 of bomb rack 8 opening jaws 10 to allow the hook to be cammed free of the jaws by tow line forces acting about the cam 12 as a fulcrum. The

hook then drops to the ground with the tow line and target and all of these parts are recovered, when possible, for reuse.

The above description, in general terms, should be sufiicient to illustrate the invention. However, an example of specific speeds, altitudes and techniques is given herein to further assist in practice of the invention, and this example is based upon use of high speed jet aircraft. Referring to Fig. 1, an aircraft 2 is flown, as at A, in the pattern shown, with hook down, and wheels and flaps up, at about 150 knots indicated air speed, 300 feet above the ground and approximately 2,500 feet abeam the pick-up point; Shortly after this, a slowly descending turn is initiated toward the pick-up course. At B, approximately 400 feet up-range of the pick-up standards, the aircraft should be wings level, indicated air speed 150 knots, lined up on the course, and at or very near the final pick-up altitude. At approximately feet from the pick-up standards, as represented by C, one-hundred percent power is achieved, and there must be no change in altiheld until an indicated air speed of knots is reached at E, at which time the aircraft is smoothly nosed over to an attitude that will permit maintaining the altitude gained. Depending on temperature and variance in technique, the altitude gained will amount to some 1,000 to 1,600 feet. 7 pensate for a high pass by being in a descent after passing C can be extremely dangerous and should be avoided.': In the interest of safety, the towing aircraft should be ballasted so that its center'of gravity is on the forward limit.

It should be obvious from the above description that this invention provides a new means and method for launching objects to be towed by aircraft, said means and method being simple in arrangement and operation and resulting in launchings free of the dangers of damage to the towed object or to the aircraft which are inherent in the known prior means and methods for accomplishing'this function.

While only a single specific illustrative example of equipment and technique has been specifically described It is emphasized that any attempt to comherein, it is obvious that many variations and modifications are possible in the light of the teachings of this disclosure. It is, accordingly, to be understood that the scope of the invention is not intended to be limited by the specific illustrative example described but rather by the scope and language of the appended claims.

What is claimed is 1. The method of eifecting aerial pickup of a grounded tow target without ground-dragging thereof, comprising the steps of: pointing said tow target down-range relative to the direction in which it is to be picked up and towed by a pickup aircraft; providing a tow line of sufiicient length to impose thereon, when the tow line is entirely raised out of ground cont-act during pickup operation, airload and inertia forces of magnitude eifective to lift said tow target without dragging effect; securing said tow line to said tow target at substantially the center of gravity thereof; extending said tow line uprange from said tow target; securing the up-range end of said tow line to a tow line loop; supporting a length of said tow line loop in position to be engaged by a pickup aircraft; restraining said tow target against the up-range displacement which tends to occur during the pickup operation; causing a pickup aircraft to fly down range toward said tow line loop; causing said aircraft to effect engagement of said loop; and causing said aircraft to climb up and over said tow target to raise the entire tow line out of ground contact and to effect lifting of said tow target.

2. A ground array of tow target apparatus for enabling a tow target to be lifted without ground-dragging during pickup operation by a pickup aircraft, said ground array of tow target apparatus comprising: a tow target pointed down-range relative to the direction in which it is to be picked up and towed; a tow line extending up-range from said tow target; said tow line having a down-range end terminating at said target and an up-range end secured to a tow line loop; means securing said downrange end to the tow target at substantially the cener of gravity thereof; a pair of pickup standards releasably supporting a length of said tow line loop above ground for engagement by the pickup aircraft; an eye element secured to said tow target at the fore end thereof; a ground-embedded stake extending upwardly through said eye element for restraining said tow target only against tip-range displacement during said pickup operation; and said tow line having a length of the order of 1800 feet such that the airload and inertia forces acting thereagainst, during a pickup operation wherein the tow line is entirely raised out of ground contact as the pickup aircraft engages said tow line loop and climbs and flies over the tow target, are effective to lift said tow target without dragging eifect.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,777 Palmer Apr. 30, 1935 2,464,073 Cotton Mar. 8, 1949 2,560,563 Fink July 17, 1951 

